1. Field of the Invention
The present invention relates to a muffler hanger used to elastically support an exhaust pipe of a vehicle on the vehicle body.
2. Description of the Related Art
A conventionally known muffler hanger is an annular member which is formed of an elastic rubber member only and in which a pair of mounting holes are formed at two opposed positions in such a manner as to extend horizontally in parallel with each other as disclosed in, for example, Japanese Utility Model Application Laid-Open (kokai) Nos. S64-44318 and H02-35921. The muffler hanger is disposed while being oriented in the front-and-rear direction of the vehicle. A pair of support shaft members are inserted into the corresponding upper and lower mounting holes so as to connect the muffler hanger to the vehicle and to an exhaust pipe, whereby the muffler hanger elastically supports the exhaust pipe on the vehicle body. In this muffler hanger, vibrations of the exhaust pipe in the right-and-left direction of the vehicle cause the muffler hanger to swing in the right-and-left direction about the upper support shaft member. As a result, the spring ratio between the spring stiffness of the muffler hanger in the vertical direction of the vehicle and that in the right-and-left direction is, for example, 1:0.2, indicating that the muffler hanger exhibits a very low spring stiffness in the right-and-left direction as compared with the vertical direction. Thus, this muffler hanger fails to sufficiently damp vibrations of the exhaust pipe in the right-and-left direction.
Another known muffler hanger is an annular member which is formed of an elastic rubber member only and in which a pair of mounting holes are formed at two opposed positions in such a manner as to extend in mutually perpendicular directions as disclosed in, for example, Japanese Utility Model Application Laid-Open (kokai) No. H02-143324. In this muffler hanger, since the paired mounting holes extend in mutually perpendicular directions, even when the exhaust pipe vibrates in the right-and-left direction of the vehicle, the muffler hanger swings rightward and leftward about the upper support shaft member in a smaller amount as compared with the case of the above-mentioned muffler hanger, in which the paired mounding holes extend in parallel with each other. However, in this muffler hanger, a portion of the elastic rubber member which connects the upper and lower mounting holes undergoes mainly shear deformation, indicating that the muffler hanger exhibits a low spring stiffness in the right-and-left direction as compared with the vertical direction of the vehicle. Further, in the above-mentioned two kinds of muffler hangers, when a considerably great rebound force is imposed thereon, the elastic rubber member may break, potentially resulting in dropping off of the exhaust pipe.
A muffler hanger designed to cope with the above-mentioned problem is disclosed in, for example, Japanese Patent Application Laid-Open (kokai) Nos. H06-93852 and 2001-328441. As shown in FIG. 10, this muffler hanger includes a generally rectangular metallic body member 1, an elastic rubber mounting portion 5, and a pair of elastic rubber supporting portions 6. The metallic body member 1 includes a bottom plate 2 and a pair of side plates 3, which form a shape resembling the letter U, and a mounting plate 4 fixedly attached to the ends of the side plates 3 and projecting outward from the side plates 3. The elastic rubber mounting portion 5 is disposed within the metallic body member 1 and has a mounting hole 5a formed therein in such a manner as to extend in parallel with the walls of the metallic body member 1. Each of the paired elastic rubber supporting portions 6 intervenes between the side plate 3 and the elastic rubber mounting portion 5 so as to elastically connect the side plate 3 and the elastic rubber mounting portion 5. This muffler hanger is mounted to a vehicle body by means of the mounting plate 4 of the metallic body member 1 while being oriented in the front-and-rear direction of the vehicle. An exhaust pipe is supported by a support shaft member fixedly inserted into the mounting hole 5a formed in the elastic rubber mounting portion 5.
Since the elastic rubber mounting portion 5 and the elastic rubber supporting portions 6 are surrounded by the metallic body member 1, even when vibrations of the exhaust pipe in the right-and-left direction are imposed on the muffler hanger, the muffler hanger does not swing in the right-and-left direction. Also, since the elastic rubber mounting portion 5 and the elastic rubber supporting portions 6 are supported by the metallic body member 1 while being enclosed within the metallic body member 1, the spring stiffness of the muffler hanger in the right-and-left direction is higher than the spring stiffness in the vertical direction. As a result, the muffler hanger can sufficiently damp vibrations in the right-and-left direction as well as vibrations in the vertical direction. Further, even when the elastic rubber member breaks as a result of imposition of an excessively large rebound force on the muffler hanger, the exhaust pipe does not drop off the vehicle body, since the support shaft member is caught by the metallic body member 1.
However, in the case of the muffler hanger including the above-mentioned metallic shell 1, since the mounting plate 4 of the metallic body member 1 is mounted to a frame of the vehicle body by use of two bolts, the cost of mounting work and the cost of parts increase as compared with the case of the above-mentioned muffler hangers formed from rubber only. Also, since the mounting plate 4 of this muffler hanger occupies a rather wide area on the vehicle body, the muffler hanger encounters a restriction related to mounting space.
An object of the present invention is to solve the above-mentioned problems and to provide a muffler hanger in which the spring stiffness thereof in the right-and-left direction is higher than the spring stiffness in the vertical direction, which is less susceptible to a layout restriction related to mounting on a vehicle body, and which is inexpensive.
To achieve the above object, the present invention provides a muffler hanger comprising a metallic body member, a tubular elastic rubber mounting portion, and a pair of elastic rubber supporting portions. The metallic body member comprises a bottom plate and a pair of side plates standing at opposite ends of the bottom plate in a facing condition. The bottom plate and the paired side plates form a generally U-like shape. A pair of first mounting holes are formed in the corresponding paired side plates at end portions of the side plates in such a manner as to face each other. The metallic body member is connected to one of a vehicle body and an exhaust pipe by means of a first support shaft member to be fixedly fitted into the paired first mounting holes. The tubular elastic rubber mounting portion is disposed within the metallic body member and in a space located between the bottom plate and the paired first mounting holes, has a second mounting hole formed therein in such a manner as to extend in the direction perpendicular to the first support shaft member, and is connected to the other of the vehicle body and the exhaust pipe by means of a second support shaft member to be fixedly fitted into the second mounting hole. The paired elastic rubber supporting portions each intervene between the side plate and the elastic rubber mounting portion so as to elastically connect the paired side plates and the elastic rubber mounting portion.
According to the present invention, the muffler hanger is disposed while being oriented in the front-and-rear direction of the vehicle, and is connected to the vehicle body and to the exhaust pipe by means of the first support shaft member fixedly attached to the metallic body member and the second support shaft member fixedly attached to the elastic rubber mounting portion and extending in the direction perpendicular to the first support shaft member. Further, the elastic rubber mounting portion and the elastic rubber supporting portions are enclosed and held by the metallic body member. Thus, when vibrations of the exhaust pipe in the right-and-left direction are imposed on the muffler hanger, the muffler hanger does not swing in the right-and-left direction and maintains its outer shape; i.e., the spring stiffness of the muffler hanger in the right-and-left direction of the vehicle is higher than the spring stiffness in the vertical direction. Therefore, the muffler hanger can sufficiently damp vibrations transmitted from the exhaust pipe; specifically, vibrations in the right-and-left direction as well as vibrations in the vertical direction. Even when the elastic rubber member breaks as a result of imposition of an excessively large rebound force on the muffler hanger, the first support shaft member and the second support shaft member are caught by each other via the metallic body member, thereby preventing the exhaust pipe from dropping off the vehicle body. Further, since the muffler hanger is mounted to a vehicle body frame by means of the first or second support shaft member, the cost of mounting work and that of mounting parts are low as compared with the case of a conventional muffler hanger which is bolted to the vehicle body frame; and the muffler hanger hardly encounters a space restriction related to mounting on the vehicle body.
Preferably, the muffler hanger further comprises an elastic rubber connection portion. The elastic rubber connection portion is disposed between the paired side plates, and comprises a pair of tubular parts and a connection part. The pair of tubular parts are fixed to peripheral portions of the first mounting holes, including wall surfaces thereof, and extend inward. The connection part integrally connects the tubular parts at least on a side toward the elastic rubber supporting portions.
Since the tubular parts of the elastic rubber connection portion are fixed to peripheral portions (including wall surfaces) of the first mounting holes, thereof, and extend inward, the first support shaft member can be readily fitted into the first mounting holes by press-fitting the first support shaft member into the tubular parts, whereby the first support shaft member is reliably fitted into the first mounting holes in a fixed condition. Also, since the elastic rubber connection portion includes the connection part provided at least on the side toward the elastic rubber supporting portions, even when an excessively large rebound force is imposed on the elastic rubber mounting portion, the connection part serves as a stopper for suppressing excessive movement of the elastic rubber supporting portions.
Preferably, the paired elastic rubber supporting portions extend from the paired side plates to the elastic rubber mounting portion while being inclined away from or toward the bottom plate and are integrally joined to opposite side walls of the elastic rubber mounting portion. Thus, while the muffler hanger is connected to the vehicle body and to the exhaust pipe, the elastic rubber supporting portions are appropriately compression-deformed.
The present invention provides another muffler hanger comprising a metallic body member, a tubular first elastic rubber mounting portion, a pair of elastic rubber supporting portions, and a second elastic rubber mounting portion. The metallic body member comprises a bottom plate and a pair of side plates standing at opposite ends of the bottom plate in a facing condition. The bottom plate and the paired side plates form a generally U-like shape. The tubular first elastic rubber mounting portion is disposed within the metallic body member, has a first mounting hole formed therein in such a manner as to extend in parallel with the inner surface of the metallic body member, and is connected to one of a vehicle body and an exhaust pipe by means of a first support shaft member to be fixedly fitted into the first mounting hole. The paired elastic rubber supporting portions each intervene between the side plate and the first elastic rubber mounting portion so as to elastically connect the paired side plates and the first elastic rubber mounting portion. The second elastic rubber mounting portion is fixedly attached to the outer surface of the bottom plate, has a second mounting hole formed therein in such a manner as to extend in the direction perpendicular to the first mounting hole, and is connected to the other of the vehicle body and the exhaust pipe by means of a second support shaft member to be fixedly fitted into the second mounting hole.
According to the present invention, the muffler hanger is disposed while being oriented in the front-and-rear direction of the vehicle, and is connected to the vehicle body and to the exhaust pipe by means of the first support shaft member and the second support shaft member which are fixedly fitted into the first mounting hole and the second mounting hole, respectively, located on opposite sides of the metallic body member and which extend in the mutually perpendicular directions. Further, the first elastic rubber mounting portion and the elastic rubber supporting portions are enclosed and held by the metallic body member. Thus, when vibrations of the exhaust pipe in the right-and-left direction are imposed on the muffler hanger, the muffler hanger does not swing in the right-and-left direction and maintains its outer shape; i.e., the spring stiffness of the muffler hanger in the right-and-left direction of the vehicle is higher than the spring stiffness in the vertical direction. Therefore, the muffler hanger can sufficiently damp vibrations transmitted from the exhaust pipe; specifically, vibrations in the right-and-left direction as well as vibrations in the vertical direction. Also, since the muffler hanger is mounted to a vehicle body frame by means of the first or second support shaft member, the cost of mounting work and that of mounting parts are low as compared with the case of a conventional muffler hanger which is bolted to the vehicle body frame; and the muffler hanger hardly encounters a space restriction related to mounting on the vehicle body.
Preferably, the paired elastic rubber supporting portions extend from the paired side plates to the first elastic rubber mounting portion while being inclined away from or toward the bottom plate and are integrally joined to opposite side walls of the first elastic rubber mounting portion. Thus, while the muffler hanger is connected to the vehicle body and to the exhaust pipe, the elastic rubber supporting portions are appropriately compression-deformed.
Preferably, the paired side plates are inclined outward, and the paired elastic rubber supporting portions extend from the paired side plates to the first elastic rubber mounting portion while being inclined away from the bottom plate and are integrally joined to opposite side walls of the first elastic rubber mounting portion. Thus, while the muffler hanger is connected to the vehicle body and to the exhaust pipe, the elastic rubber supporting portions are appropriately compression-deformed, and the outwardly inclined side plates appropriately receive the compression deformation of the elastic rubber supporting portions.